LAS VEGAS — Late last week, thanks to a tweet both misplaced and misconstrued, Roger Mason Jr. became the inadvertent face of hope in the NBA players union’s ongoing labor battle with league owners.

By Wednesday afternoon, hope had seemed to vanish from Mason’s vocabulary.

Calling the good vibes that led up to Tuesday’s stalled bargaining session with owners “a false sense of optimism,” Mason — vice president of the players union and a former Spurs guard — said there was “absolutely” a possibility the entire 2011-12 season will be erased by the lockout.

“I’m an optimistic person at heart,” Mason said after a game in the Impact Competitive Basketball Series in Las Vegas. “But what would make me think we’d have a season?”

Today, Mason and other union bigwigs — including executive director Billy Hunter and president Derek Fisher — will deliver a similarly dreary forecast to an estimated 80 players set to gather here for a labor briefing that some believe could devolve into full-scale revolt.

On the surface, Mason’s pessimism appears at odds with a post that briefly appeared on his Twitter account last week, which read in part: “Looking like a season.” Many observers took the tweet to be a leak that significant progress had been made in closed-door negotiating sessions.

Initially, Mason claimed his account had been hacked. Wednesday, he said the tweet had been accidentally posted by one of his representatives without his knowledge.

Chillingly, Mason says the post was not a sign of optimism at all. It came, he said, in answer to the question: “How long is the lockout going to last?”

After union leaders left the bargaining table Tuesday in New York with the owners still clinging to the idea of a hard salary cap, Mason’s answer to that question hasn’t changed.

“Right now, it’s looking like we’re going to miss training camp and some preseason games,” Mason said. “Unless some things change, we could lose the season. There’s no reason for me to think otherwise.”

With nervousness growing among players about Hunter’s job performance, and with a powerful cartel of agents saber-rattling to decertify the union, Mason is bracing for a meeting with fellow players today that could become contentious.

At about the same time, owners will hold a Board of Governors briefing in Dallas, with a group that includes the Spurs’ Peter Holt, head of the NBA’s labor committee.

Reiterating the union was still steadfast against decertification, a so-called “nuclear option” that would drag out in court, Mason issued a call for harmony among players.

“We just need to be on the same page,” Mason said. “We don’t need a contingent of agents pushing for one thing and the union pushing for another. Anytime there’s turmoil on one side of the negotiation, it hurts you. I’m sure (owners) would love to have dissension among us.”